Saturday, February 3, 2018

Systematic Approach for Testing & Commissioning of Newly Constructed Alumina Refinery

Hi Friends,

We are well aware that Alumina refinery is a continuous hydro-metallurgical process involving complicated unit operations and unit processes. Testing & commissioning is the 5th stage in execution of new Alumina refinery which comes after Basic engineering, Detail engineering, Procurement and Erection ensuring mechanical completion. Safe and smooth startup of Alumina refinery with due care of human safety, equipment, process input materials and environment are the basic objectives of successful testing and commissioning of Alumina refinery. Thus, successful commissioning of Alumina refinery has five basic objectives as listed below-
·        No loss time accident,
·        No equipment damage,
·        No risk to environment,
·        No wastage of input materials and
·        Stabilization of plant within shortest period.

Sequence of testing and commissioning of Alumina refinery include following major steps-

Field Checking and Punch Listing: 
Field checking of construction completion status of all equipment, instruments, electrical and associated facilities of Alumina refinery, Co-generation plant, Water supply system, Power distribution system, Compressed air system, cooling tower and Distributed control system is carried out before testing and commissioning of technological plant and equipment. Based on field checking, a list of required additions / deletions / modifications and design changes are recorded with specific identification number for rectification on planned manner as per priority decided by a team of senior technical professionals of the plant.

System Configuration Checking:
You must have gone through the paper on Execution of Alumina refinery on EPC Methodology. Soon after completion of erection activities and before commencement of testing and commissioning trials, system configuration checking is considered to be one of the important steps. This step is the visual inspection of technological and services equipment as per PFDs, P&IDs, ISOs, specifications and design drawings to ensure their readiness for cold water trials. System configuration checking includes the verification of following-
·        Proper installation of equipment,
·        Fixing of valves and pipelines,
·        Alignment and lubrication of rotating equipment,
·        Direction of rotation of motors,
·        Sealing arrangement of pumps,
·        Proper connections of electrical power supply system.

Checking of Instrumentation and Control System: 
This activity is carried out to ensure the readiness of Instrumentation and control system with respect to following critical aspects-
·        Installation of all instruments and controls as per P&IDs,
·        Setting of alarms and tripping system,
·        Process and Safety interlock system,
·        Microprocessor signals,
·        Functioning of local and remote sensing equipment,
·        Correct relay of data / information from field instruments to local as well as Central control rooms,

Checking Cleanliness of Process Vessels and Pipelines: 
This task is carried out by flushing out the process vessels and pipelines to ensure removal of obstruction and blockages in the process circuit just before cold water test run.

Checking of Auxiliary System: 
Performance of auxiliary system like Air conditioners, exhaust fans and connected ducts are checked to ensure desired working environment for instruments, controls, equipment and operating personnel.

Training of Plant Operating Supervisors and Operators: 
Objective of training of supervisory staffs and plant operators is to guide them to commission the Alumina refinery safely. It involves following steps-
·        Formation of team comprising of Managers of various disciplines / departments headed by an Expert.
·        Train the Supervisors aiming to ‘Train the Trainer’ who will train the operators,
·        Review the startup and commissioning procedures,
·        Educating the team with operating and process control parameters including benefits and consequences,
·        Provide technical leadership to facilitate safe, reliable and steady operation of Alumina refinery.
Process and Operating Manual for Systematic Start up: 
This document includes the estimated requirement of input materials and stepwise process sequence for meeting the following basic requirements-
·        Planning for required quantity of input materials,
·        Readiness of Area wise log sheets
·        Fixing the responsibilities of individuals in commissioning team,
·        Normal plant start up procedure,
·        Normal shut down procedure,
·        Emergency plant shut down procedure,
·        Plant Inventory procedure,
·        Procedure for increasing the plant volume steadily,
·        Method for increasing temperature profile of process stream,
·        Guidelines for ensuring adequate supply of condensate to cogeneration plant,
·        Sequence for raising concentration profile of process streams,
·        Planning for aluminate liquor generation and seed charge to initiate generation of seed,
·        Recycling of seed to regular precipitation circuit,
·        Production of hydrate and product alumina.
·        Stabilization of operation of Alumina refinery.

Start up and commissioning of Alumina Refinery:
Bauxite charge to process is considered as the zero date for startup and commissioning of Alumina refinery which is done after caustic concentration build up in selected process vessels to start with for generation of spent liquor and aluminate liquor subsequently. Seed charge enhances the precipitation efficiency thereby generation of seed and product hydrate. Steady control on process and operating parameters stabilizes the plant resulting in target production rate. Calciner is generally commissioned after creating adequate stock of hydrate in the storage shed.
Performance Tests for Plant and Equipment: 
Test runs are conducted with standard agreed procedure for individual plant, equipment and facilities in order to assess the guaranteed performance. However, performance tests for entire Alumina refinery are carried out after stabilization of plant operation to check the assigned production rate and efficiency parameters as agreed by technology supplier, equipment supplier and engineering consultant. 

The above stated guidelines are generally followed for systematic testing, start up and commissioning including establishing performance guarantee parameters of newly constructed Alumina refinery.

Hope, you will like to have a look at the article on "Engineering and execution stages of Alumina refinery."
Best regards.

Rajendra Kunwar


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